1. Field of the Invention
The present invention relates to a vehicle and, in particular, to a vehicle provided with a front frame for supporting a front wheel and a rear frame for supporting a rear wheel.
2. Description of Related Art
Some vehicles, such as motorcycles, are provided with a front frame for supporting a front wheel and a rear frame for supporting a rear wheel. Conventional motorcycles are provided with front forks that absorb shock in the vertical direction. The front forks are installed in part of the front frame for supporting the front wheel. With this structure, the front forks can absorb shock in the vertical direction when the front wheel encounters shock in the vertical direction due to bumps or potholes on the ground while the vehicle is running straight ahead with the front wheel not inclined.
With the front forks in the conventional motorcycles as described above, shock applied to the front wheel in the vehicle's vertical direction can be absorbed. However, it is difficult to absorb shock applied thereto in the vehicle width direction. Thus, with conventional front forks, it can be difficult to absorb shock when the front wheel encounters shock in the vehicle width direction due to bumps or potholes on the ground during a turn with the vehicle body (front wheel) inclined,.
On the other hand, another type of conventional motorcycle has been proposed in which the front frame for supporting the front wheel is rotatable with respect to the rear frame for supporting the rear wheel (see JP-A-Sho 63-222987, for example). In JP-A-Sho 63-222987, shock in the vehicle width direction can be mitigated to some degree when shock in the vehicle width direction due to bumps or potholes on the ground is applied to the front wheel during a turn with the vehicle body (front wheel) inclined,.
However, in the structure proposed in JP-A-Sho 63-222987 when shock in the vehicle width direction is applied to the front wheel, the front wheel only moves in the direction in which the shock has been applied (the vehicle width direction) to absorb the shock. That is, the shock in the vehicle width direction is not actively absorbed, and it is still difficult to sufficiently absorb the shock in the vehicle width direction.